Polyamine aminopropyltransferase

UniProtKB accession:  Q5SK28

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UniProtKB description:  Involved in the biosynthesis of polyamines which are thought to support the growth of thermophilic microorganisms under high-temperature conditions. It seems that long-chain and branched-chain of polyamines effectively stabilize DNA and RNA, respectively. Catalyzes the irreversible transfer of a propylamine group from the amino donor S-adenosylmethioninamine (decarboxy-AdoMet) to agmatine to yield N1-aminopropylagmatine. An efficient aminopropyltransferase activity has been also observed with norspermidine which produces thermine, and spermidine which produces spermine and thermospermine. The aminopropyl activity with homospermidine, mitsubishine, thermine, 1,3-diaminopropane, putrescine (1,4-diaminobutane), spermine and caldopentamine are very low. The reaction involves a nucleophilic attack on the C-3 methylene of the propylamine moiety adjacent to the positively charged sulfur of decarboxy-AdoMet.